The present invention relates to a head-mounted projection display system providing a wide field of view with unlimited binocular overlap or unlimited field of view through limited binocular overlap, more particularly, to both systems featuring a beam splitter.
Experience is expensive. Particularly, when the experience involves man-machine interface between a skilled pilot and a multi-million dollar aircraft.
Today's high performance aircraft have become more and more complex, and a need exists for more extensive specialized pilot training. To obtain such training an inexperienced pilot, commercial or military, must either actually be trained in the aircraft he is to fly or be provided with training in a simulator for that aircraft.
However, there are certain emergency procedures and maneuvers that, as a practical matter, simply cannot be experienced by training in an actual aircraft because of the real life danger of pilot injury or structural damage. Consequently, as a practical matter, some situations can only be experienced in a simulator. This is particularly true of maneuvers that involve emergency procedures.
Aircraft simulators are called upon to take on more and more of the aircraft training mission. For such training to be effective, the aircraft simulator must faithfully reproduce the simulated environment that the pilot trainees face in an actual flight. The pilot must "see" the terrain over which he flies. He must appreciate obstacles on the ground as well as in the air. Through his eyes, his brain must assimilate visual images and cues received from the simulated environment surrounding his aircraft.
The desire to more effectively support pilot vision in both a field of view and image resolution of the simulated environment has led to the development of a wide variety of simulator display concepts.
One approach provides a projection simulator display achieving wide field of view by incorporating several large, expensive projectors collectively producing an image on the inside of a 20 to 40-foot dome to be viewed by an observer located close to the dome center.
U.S. Pat. No. 4,657,512, issued Apr. 14, 1987 to R. A. Mecklenborg, entitled, "Visual System with Filter for a Simulator" describes a vehicle simulator display system for training two observers such as a pilot and co-pilot seated side-by-side viewing compound images projected on a large curved screen. Structurally, the display system includes two projectors, each of which uses a polarizer to polarize the individual light images in opposite directions in a circular manner. The vehicle simulator display system of the Mecklenborg patent uses two large off-screen projectors pointed at a large dome-like reflective screen. A reflective viewing screen is curved and specially treated to reflect impinging light energy. The Mecklenborg display system provides a wide field of view to the screen observers. However, the cost of an overall display system is exorbitant due to the large off-screen projectors and domed retro-reflective screen. And, the conventional multiple projector process produces only reasonable scene brightness.
An alternative method, using head or helmet-mounted displays, reduces the overall system cost and enables increasing projected scene brightness by projecting the simulated image directly into the observer's eye.
U.S. Pat. No. 4,349,815 issued Sep. 14, 1982, to A. M. Spooner, entitled, "Head-Movable Frame-Scanner for Head-Coupled Display", describes a helmet-mounted display system using a curved retro-reflective screen and two image projectors.
Unfortunately, in the inexpensive helmet-mounted system, the requirements for comfortable observer viewing, good eye relief, reasonable pupil size and full binocular viewing are not compatible with the desired wide fields of view. Field of view for a helmet-mounted display system conventionally is limited to 20 to 60 degrees for each eye. Visual fields traditionally have been achieved only by providing each eye with a separate field that results in limited binocular overlap.
It would be advantageous to combine the best features of both the projection and the helmet-mounted displays to produce a wide field of view display with an inset format and provide comfortable observer viewing and low overall system cost.